Throttle body assemblies provide aspiration to engines. The aspiration to these engines is controlled through a throttle plate disposed in a bore of the throttle body assemblies. The throttle plate is manipulated by a user of the engine to cause increase or decrease airflow to the engine thereby controlling power output.
As part of an overall engine control system, and in certain applications a vehicle control system, the operation of the throttle body assembly is monitored to provide vital information to the control system. For example, as part of an overall monitoring system of an engine, it is desirous to monitor the position of a throttle plate to ensure that the throttle body assembly is functional and performing properly. Also, by determining the position of the throttle plate it is possible to determine efficiency of the engine by comparing anticipated power output to actual power output. Other information can be determined, as well.
In the past, positions of throttle plates have been determined using throttle position sensors. These sensors utilized induction formed between a component of the throttle plate and a sensor. More particularly, a sensor element is mounted to a shaft, in which the throttle plate has been mounted to, and is placed in an inductive relationship with an inductive rotary position sensor such that position of the sensor element relates to a position of the throttle plate.
Unfortunately, due to its electrical components and inductive relationship the throttle position sensor is susceptible to spikes in electric currents and/or voltages. Such spikes are often inherent to the operation or maintenance of an engine. For example, static electricity generated by airflow through the throttle body assembly, an engine maintenance person's touch, or otherwise, has the potential to generate a spark with a sensor, which can potentially cause damage to electric components. Also, the accumulation of potential energy such as residual electric charge and the discharge of such potential energy can effect measurements and operation of the throttle position sensor.
Prior throttle position sensors have attempted to solve this problem by developing complicated grounding means for the sensor. However, not only have these arrangements added considerable cost to the throttle body assembly, but the also transfer of accumulated charge across the sensor can be potentially damaging to the sensors. Also, some systems allow for periodic discharge of accumulated charge; however, it has been recently discovered that the elimination of any charge across the sensor increases accuracy of the throttle position sensor.
In view of the foregoing, there is a need for improved methods and devices to reduce or eliminate potential damage to a throttle position sensor caused by the accumulation and discharge of residual electric charge.